Fire damage to life and property is a problem wherever it occurs, but it is a particularly acute problem in transportation vehicles on land, on and under the seas, and in the air, where fireproofing materials are necessarily limited to minimal weights and volumes.
A recent development in fire retardance, disclosed in said application Serial No. 103,064, comprises a flexible laminate of a support layer and an attached cured silicone foam rubber layer containing alumina trihydrate, which laminate has a surface flammability flame spread index of zero at 20 minutes of exposure in accordance with ASTM E-162 and is capable, in a thickness of 1/16 inch, of blocking a flame of 1050.degree. C. for more than one hour.
This flexible laminate can be adhered, or otherwise attached, to any fire susceptible surface and can thereby retard the spread of a fire until steps can be taken to bring the fire under control.
In many places, however, it may be desirable to retard the spread of a fire where there is no underlying surface to which to attach the aforesaid flexible laminate. There is therefore need for a light weight and small volume fireblock sheet which is rigid and self-supporting.